A basic process to prepare high molecular weight alpha olefins from ethylene is disclosed in aforementioned U.S. Pat. No. 3,647,906, to Farley. This process discloses the combinative treatment of oligomerization of ethylene followed by requisite separation, then isomerization and disproportionation of light olefins and heavy olefins derived from the separation zone. In this manner the specific carbon range of alpha olefins sought is maximized and the refiner's profit margin is greatly increased. All of the specific teachings of this patent are herein incorporated by reference. In the procedure wherein alpha olefins are isomerized to internal olefins, a catalyst is employed which preferably has little or no polymerization or cracking activity. Suitable examples are exemplified as phosphoric acid, bauxite, alumina supported cobalt oxide, or iron oxide or manganese oxide. Other suitable isomerization catalysts are disclosed by the publication "Review of Olefin Isomerization" (H. N. Dunning, Industrial and Engineering Chemicals, 1953). Other isomerization catalysts such as a combination of sodium and potassium on alumina can also be utilized for this type of isomerization process.
In U.S. Pat. No. Re. 28,137 a process is described for preparing an olefin from two dissimilar acyclic olefins in a disproportionation process. It is disclosed that double bond isomerization may occur during this disproportionation. The catalyst for such reactions is a mixture of molybdenum oxide and alumina containing cobalt oxide and optionally containing minor amounts of alkali metal or alkaline earth metal ions. Also, suitable rhenium heptoxide is utilized in these type of disproportionation reactions. Such molybdenum or rhenium catalyst prepared on a support comprising various forms of alumina are exemplified in U.S. Pat. No. 3,471,586, Lester.
Types of aluminosilicates have previously been used for skeletonal isomerization of hydrocarbon molecules including olefins. U.S. Pat. Nos. 4,217,240; 4,257,804; and 4,272,409 are exemplary of certain isomerization catalysts. An article in the Journal of Catalysis, Volume 92 (1985), describes the use of a ZSM-5 zeolite for the isomerization of 1-hexene. The double bond shift discovered therein formed both the cis- and trans-2-hexene. The skeletal rearrangements which give cis-3-methyl-2-pentene and trans-3-methyl-2-pentene are the result of the skeletal rearrangements of the hexene-1. The performance of the ZSM-5 zeolite was found to be comparable to the catalytic isomerization of 1-hexene in the presence of an HY zeolite while the rate of conversion was substantially less. See also Wojciechowski et al, International Journal of Chemical Kinetics Vol. 15 (1983) and Abbot, Canadian Journal of Chemical Engineering Vol. 63 (1985), Catalytic Cracking and Skeletal Isomerization of N-hexene on ZSM-5 Zeolite. In October 1985, Abbot and Wojciechowski discussed the summary of the catalytic reactions of normal hexenes in the presence of amorphous silica-alumina. See the Canadian Journal of Chemical Engineering, Vol. 63 (1985). The predominant isomerization is skeletal with very low initial selectivity to cracking. The slowness of reaction to paraffins and dehydrogenated species is attributed to a small number of strongly acidic sites on the amorphous material. The skeletal isomerization is specifically discussed at page 819 of that article.
A ferrierite aluminosilicate is exemplified by U.S. Pat. Nos. 4,016,245 and 4,343,692 although the catalyst of the latter patent is taught as piperidine-derived and is useful in a catalytic dewaxing process. Incorporated by reference herein is the disclosure of Nanne et al, U.S. Pat. No. 4,251,499, which describes the preparation of a piperidine derived ferrierite. Also, an ethylenediamine and pyrollidine derived ferrierite is exemplified in aforementioned U.S. Pat. No. 4,016,245.
A method for the production of surface modified zeolites was disclosed in U.S. Pat. No. 4,451,572, issued to Cody, all of the teachings of which are herein incorporated by reference. Specific references can be made to Col. 8 and 9 for the technique of how to perform the silylation. The organosilanes of the general formula: EQU SiRyX.sub.4 -y
and
(RwX.sub.3-w Si).sub.2 -Z are useful as feasible silylation agents wherein:
y=1 to 4 PA1 w=1 to 3 PA1 R=alkyl, aryl, alkoxy, arylalkyl, and where R has from 1 to 10 carbon atoms PA1 x=halide and PA1 Z=oxygen, NH- or substituted amines or amides.
The zeolites treated by this silylation technique to modify their surface are typical large pore zeolites as exemplified by X, Y, and ZSM-5 aluminosilicates. There is not present the disclosure of treating an aluminosilicate having a ring structure commensurate with an 8 and 10 member ring channel. There is also no recognition that the treatment of the aluminosilicates will diminish dimerization reactions in an olefin isomerization reaction.